Good stuff. Thanks for the easy to understand explanation. This video provides a very clear overview. Also, great audio quality and production value. Well done!
Sorry for the delay. I was busy making another video. Thank you for the feedback. It’s good to know the effort helps people. The reward is in the giving. Thank you! 73
I think some clarification of terms is needed. Duplex refers to a two way comms. Full duplex is where both parties can send and receive simultaneously - like on your telephone. Half-duplex is when either party can be sending, but only one at a time, like we do with our direct radio to radio comms. Simplex usually refers to broadcast - your favorite FM station - a one way communication. So even with the repeater, our ham comms are half-duplex, just as line of sight comms would be.
I agree. It seems some radio manufacturers refer to repeater mode as duplex, which just adds to the confusion. In my experience, I’ve only known it as simplex or repeater. From what I’ve been told, I think it’s either commercial radios or GMRS radios that may be calling it duplex. I thought I’d mention it in the notes. Hopefully it doesn’t cause more harm than good. I appreciate the feedback.
That's a good comment. In daily conversation, it's rarely referred to as duplex when spoken and referring to using a repeater. The radio menus often call it duplex (or repeater), so perhaps an additional reference to it would be helpful.
I just realized I didn't reply to your question. My apologies. There are some radios that can operate in full-duplex mode. Not hand held radios though. Mobile radios such as commercial grade Motorola and GE are two famous ones for being modified to operate when they can listen and transmit at the same time. These radios are used often for repeater use on mountain tops. They are also used by some hams in full duplex so they can hear themselves as they sound from the repeater. You can usually hear the duplex audio in the background as they speak.
Sorry for the delayed reply-I had work distractions. The setting for repeater vs simplex is usually programmed into a memory channel, found in the menu as a transmit option, or sometimes a knob on the radio. If it’s stored in a memory channel, it will operate on whatever mode it was stored as. For example, it’s possible to have adjacent channels configured so that channel 1 is set up as simplex and channel 2 is repeater. A simplex channel will transmits and receive on the same frequency. A repeater frequency or channel will transmit on different frequencies. That difference is called a transmit offset, and is automatically controlled by the radio, but it has to be told to do that. That’s where the menu selection for repeater mode is important. In the UHF band, the repeater split or transmit offset is usually 5 mhz. So for example, in Southern California, we would listen on our radio on 447.000 mhz, and transmit on 442.000 mhz. It’s low in/high out from the repeater. A 5 mhz split or offset. In other parts of the USA, and GMRS, it’s the opposite 5 mhz split. In high/out low from the repeater, or, transmit 447.000 and listen on 442.000. A GMRS radio might be something like 467.550 transmit and 462.550 receive. High in/low out from the repeater. Again, 5 mhz split. The two-meter ham band uses a 0.600 mhz repeater offset. Same idea, but a different split for the repeater input. Not 5 mhz. Ex: Transmit to the repeater on 146.370 / Receive on 146.970. I hope that makes sense.
Good stuff. Thanks for the easy to understand explanation. This video provides a very clear overview. Also, great audio quality and production value. Well done!
Thank you! I appreciate the feedback.
Just about the simplest way to illistrate Simplex and Repeater. Thanks de K0MRD
Sorry for the delay. I was busy making another video.
Thank you for the feedback. It’s good to know the effort helps people. The reward is in the giving.
Thank you!
73
Very useful info, thanks!
I’m happy it helped you.
I think some clarification of terms is needed. Duplex refers to a two way comms. Full duplex is where both parties can send and receive simultaneously - like on your telephone. Half-duplex is when either party can be sending, but only one at a time, like we do with our direct radio to radio comms. Simplex usually refers to broadcast - your favorite FM station - a one way communication.
So even with the repeater, our ham comms are half-duplex, just as line of sight comms would be.
I agree. It seems some radio manufacturers refer to repeater mode as duplex, which just adds to the confusion. In my experience, I’ve only known it as simplex or repeater. From what I’ve been told, I think it’s either commercial radios or GMRS radios that may be calling it duplex. I thought I’d mention it in the notes. Hopefully it doesn’t cause more harm than good. I appreciate the feedback.
Thank you!
You are very welcome! Hope it helps you.
the word opposite to the simplex could be a duplex? It is not clear from the video whether this is the case with radio communications.
That's a good comment. In daily conversation, it's rarely referred to as duplex when spoken and referring to using a repeater. The radio menus often call it duplex (or repeater), so perhaps an additional reference to it would be helpful.
@@Raymazon whether full duplex is the term? if some radios play two frequencies at the same time, is it possible to listen while talking?
this is probably not a question of frequency but of signal strength in the antenna..
I just realized I didn't reply to your question. My apologies. There are some radios that can operate in full-duplex mode. Not hand held radios though. Mobile radios such as commercial grade Motorola and GE are two famous ones for being modified to operate when they can listen and transmit at the same time. These radios are used often for repeater use on mountain tops. They are also used by some hams in full duplex so they can hear themselves as they sound from the repeater. You can usually hear the duplex audio in the background as they speak.
So it's automatic? or manual?
Sorry for the delayed reply-I had work distractions.
The setting for repeater vs simplex is usually programmed into a memory channel, found in the menu as a transmit option, or sometimes a knob on the radio. If it’s stored in a memory channel, it will operate on whatever mode it was stored as. For example, it’s possible to have adjacent channels configured so that channel 1 is set up as simplex and channel 2 is repeater.
A simplex channel will transmits and receive on the same frequency. A repeater frequency or channel will transmit on different frequencies. That difference is called a transmit offset, and is automatically controlled by the radio, but it has to be told to do that. That’s where the menu selection for repeater mode is important.
In the UHF band, the repeater split or transmit offset is usually 5 mhz. So for example, in Southern California, we would listen on our radio on 447.000 mhz, and transmit on 442.000 mhz. It’s low in/high out from the repeater. A 5 mhz split or offset.
In other parts of the USA, and GMRS, it’s the opposite 5 mhz split. In high/out low from the repeater, or, transmit 447.000 and listen on 442.000.
A GMRS radio might be something like 467.550 transmit and 462.550 receive. High in/low out from the repeater. Again, 5 mhz split.
The two-meter ham band uses a 0.600 mhz repeater offset. Same idea, but a different split for the repeater input. Not 5 mhz.
Ex: Transmit to the repeater on 146.370 / Receive on 146.970.
I hope that makes sense.